United States Patent Specification US 4285714 describes a method in which a glass plate is connected to, for example, a semiconductor body by means of electrostatic bonding at a temperature in excess of the softening temperature of the glass. The electric potential applied amounts to approximately 1000 V at a temperature from 450.degree. to 800.degree. C. In the bonding process, the parts to be interconnected are brought into contact with each other under pressure.
The high temperature and the high electric voltage render this known method unsuitable for the manufacture of a device which prior to bonding is provided with active semiconductor elements which may be damaged in the bonding process. The method is also less suitable for the manufacture of an optical device in which it is desirable for the layer of light-conducting material to be completely plane and plane-parallel, which is very difficult to control at temperatures in excess of the softening temperature. Moreover, if a crystalline optical material or quartz glass is used in the optical device the softening temperature is so high that the known method cannot be applied A layer of quartz glass can also be obtained by means of an alternative method, for example by means of chemical deposition from the vapor phase; however, in this case it is difficult to obtain a layer of a sufficiently high optical quality. It is possible to grow a layer of silicon dioxide on a silicon substrate by means of oxidation, but it is difficult to obtain a layer which has a sufficient thickness, for example, in excess of 10 .mu.m.